A water-cooled type battery system configured to cool a battery through a cooling channel may undergo breakdown of inside insulation of the battery caused by an AC voltage at the time of motor 3-phase insulation breakdown, and has a higher possibility of AC insulation breakdown than that of DC insulation breakdown. In a process of development, the water-cooled type battery system may have vulnerable AC voltage insulation although it has sufficient DC voltage insulation.
The conventional water-cooled type battery systems have a grounded cooling channel (cooling plate). Therefore, it is more difficult to ensure the insulation performance of the water-cooled type battery system than that of an air-cooled type battery system. Further, in the water-cooled type battery system, a distance between a cooling channel and a battery cell is short in order to improve the cooling performance thereof. Therefore, the water-cooled type battery system is more susceptible to explosion during cell venting than the air-cooled type battery system. Further, it is difficult to ensure the insulation of the water-cooled type battery system when a relay of a high-voltage battery thereof is in a fused state.
In order to ensure AC insulation, the water-cooled type battery system is required to have a chassis and a battery sufficiently spaced from each other. However, when the chassis and the battery are sufficiently spaced from each other, the efficiency of the water-cooled type battery system is inevitably reduced. Further, the water-cooled type battery system has an airtight structure and thus has a safety-related problem, such as explosion, which may be caused by an insulation breakdown during cell sealing release.
Therefore, there has been a necessity for a solution for solving the insulation vulnerability resulting from the above structure of the water-cooled type battery system.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and should not be taken as acknowledgement that this information forms the prior art that is already known to a person skilled in the art.